2014 Annual Science Report

Executive Summary

This is an interdisciplinary investigation of prebiotic chemistry on Titan in the context of Titan’s physical environment to provide a basis for understanding the prebiotic chemistry of the early Earth. Although Titan is far from the Sun and hence cold, solar radiation interacts with the methane rich atmosphere to initiate the formation of complex organic molecules and aerosols that eventually deposit on Titan’s geologically active surface, where further chemical evolution leading to the origin of life could occur.

The work comprised three parts or themes. The first theme, the current Titan physical environment, was aimed at understanding the basic physical processes that couple the surface and atmospheric chemistry of Titan. In the second theme, the complexity of atmospheric organic chemistry, employed experimental and theoretical tools to explore the range of atmospheric organic molecules that can be generated both in the gas-phase and in the condensed ... Continue reading.

Project Reports

Low-energy electron-beam irradiation and dissociative electron attachment (DEA) experiments were performed on nitrogen-containing organic condensates as a model for cosmic-ray induced polymerization processes and charging events that can occur within Titan’s atmosphere and on Titan’s organic-rich surface. In addition, detailed analysis of meteorite surfaces were analyzed with an emphasis of understanding the corrosion of schreibersite and the role this may play in the formation of phosphorylated pre-biotic molecules.

Using analytical methods including nuclear magnetic resonance spectroscopy, mass spectrometry and non-aqueous microchip gel electrophoresis, we investigate the properties and structure of the major components of laboratory analogues of Titan tholins.

To develop a comprehensive model of the chemistry in Titan’s atmosphere including condensation of molecules onto grains and sublimation back to the gas, and exchange between the atmosphere and surface.

We have discovered that benzene and ethane form a co-crystalline inclusion compound at Titan surface temperatures and pressures. Co-crystals of other organic compounds could be common on Titan’s surface. These results can help explain the release of ethane observed at the Huygens landing site, and point to a new type of surface material that may have significant impact on Titan surface chemistry and geology.

Planetariums have a long history of experimentation with audio and visuals to create new multimedia experiences. We report on a series of innovative experiences that began in the Gates Planetarium at the Denver Museum of Nature & Science, combining live performances of music and navigation through scientific visualizations. The Life Out There productions featured a story showcasing astrobiology concepts at scales ranging from galactic to molecular, and told using VJ-ing of immersive visualizations and musical performances from the House Band of the Universe. These hour-long shows were broken into four separate themed musical movements, with an improvisatory mix of music, dome visuals, and spoken science narrative which resulted in no two performances being exactly alike. Post-performance dissemination is continuing via a recorded version of the performance available as a DVD and online streaming video. Written evaluations from visitors who were present at the live shows reveal high satisfaction and subsequent interest in astrobiology topics. Life Out There concerts have been used to inaugurate a new evening program to draw in a younger audience demographic to DMNS, and have been taken on the road to other venues in other cities.

We continued the development and public presentation of this live digital planetarium show about Titan and Astrobiology. This live lecture planetarium show, entitled “Life Out There” makes use of the digital imaging capabilities of the dome, through the innovative Uniview software, a “real time” virtual simulation of the known universe based on accurate astronomical databases and modeling. The inclusion of live musicians, who serve to introduce each section of the show, helps to attract an audience beyond those who reliably come to space science events at the planetarium, and help to create a relaxing and evocative atmosphere conducive to wonder and learning. With Uniview, we can utilize the SPICE Kernels that spacecraft teams use to describe mission trajectories, and create virtual versions that can be followed along through the simulation. Using 3-D spacecraft models, the public can follow spacecraft missions shown with breathtaking realism within the immersive display. We have a detailed model of the Cassini spacecraft, and we are using the most recently updated SPICE kernels of Cassini, including the many Titan flybys, to show the public the fantastic journey of Cassini and Huygens in exploring Titan. In addition to the live lecturer, a second operator controls the Uniview software, allowing these flybys to be seen from any perspective deemed instructive and/or entertaining. Various Cassini and Huygens image data sets, including camera data, infrared spectrometer data and radar data, are being texture mapped and rendered on the moon’s surface. The atmosphere is visually peeled away, and various visuals are used together with an original script and musical score, both written by E/PO lead David Grinspoon, to explore themes of Titan and Astrobiology for the public. The visual content was directed by Dr. KaChun Yu, Curator of Space Sciences at DMNS, in collaboration with Dr. Grinspoon.

We developed, tested, evaluated and disseminated a 20-minute stage show for informal science centers to excite and inform visitors about the science and exploration of Titan. The show utilizes a participatory exercise in scientific illustration to engage visitors in the material. Each participant is given a clipboard and pencils, and the facilitator, using a series of Cassini and Huygens images and videos of Titan, leads them through an exercise in which each draws a sketch of a Titan landscape, learning along the way about many aspects of the Titan environment as revealed by modern exploration. The show has now been seen by many thousands of visitors to the Denver Museum of Nature and Science.

During this last year we focused on disseminating the presentation materials and supporting media, and training materials, including a training DVD for presenters for use at other informal science centers.

We continued the development and public presentation of a live digital planetarium show about Titan and Astrobiology. This live lecture planetarium show, entitled “Life Out There” makes use of the digital imaging capabilities of the dome, through the innovative Uniview software, a “real time” virtual simulation of the known universe based on accurate astronomical databases and modeling. The inclusion of live musicians, who serve to introduce each section of the show, helps to attract an audience beyond those who reliably come to space science events at the planetarium, and help to create a relaxing and evocative atmosphere conducive to wonder and learning. With Uniview, we can utilize the SPICE Kernels that spacecraft teams use to describe mission trajectories, and create virtual versions that can be followed along through the simulation. Using 3-D spacecraft models, the public can follow spacecraft missions shown with breathtaking realism within the immersive display. We have a detailed model of the Cassini spacecraft, and we are using the most recently updated SPICE kernels of Cassini, including the many Titan flybys, to show the public the fantastic journey of Cassini and Huygens in exploring Titan. In addition to the live lecturer, a second operator controls the Uniview software, allowing these flybys to be seen from any perspective deemed instructive and/or entertaining. Various Cassini and Huygens image data sets, including camera data, infrared spectrometer data and radar data, are being texture mapped and rendered on the moon’s surface. The atmosphere is visually peeled away, and various visuals are used together with an original script and musical score, both written by E/PO lead David Grinspoon, to explore themes of Titan and Astrobiology for the public. The visual content was directed by Dr. KaChun Yu, Curator of Space Sciences at DMNS, in collaboration with Dr. Grinspoon.

In 2007, NASA sponsored a committed of the National Academies of Science to explore whether life might exist in environments outside of the traditional habitable zone, defined as positions in a solar system where liquid surface water might be found. Alternative solvents which have analogous “habitable zones” farther away from their star include hydrocarbons, ammonia, and dinitrogen. The core question asked whether life having genetic biopolymers might exist in these solvents, which are in many cases (including methane) characterized by the need for “cold” (temperatures < 100K in the case of methane).

These “weird” solvents would require “weird” genetic molecules, “weird” metabolic processes, and “weird” bio-structures. In pursuit of this “big picture” question, we turned to Titan, which has exotic solvents both on its surface (methane-hydrocarbon) and sub-surface (perhaps super-cooled ammonia-rich water). This work sought genetic molecules that might support Darwinian evolution in both environments, including non-ionic polyether molecules in the first and biopolymers linked by exotic oxyanions (such as phosphite, arsenate, arsenite, germanate) in the second.

In the current year, we completed our studies that identified biopolymers that might work in hydrocarbon solvents. These studies have essentially ruled out biological processes in true cryosolvents. However, a series of hydrocarbons containing different numbers of carbon atoms (one, two, three, and four, for example, in methane, ethane, propane, and butane) cease to be cryosolvents as their chain lengths increase. These might be found on “warm Titans”. Further, they might exist deep in Titan’s hydrocarbon oceans, where heating from below would lead to warm hydrocarbon oceans.

These studies showed that polyethers are insufficiently soluble in hydrocarbons at very low temperatures, such as the 90-100 K found on Titan’s surface where methane is a liquid at ambient pressures. However, we did show that “warm Titans” could exploit propane (and, of course, higher hydrocarbons) as a biosolvent for certain of these “weird” alternative genetic biopolymers; propane has a huge liquid range (far larger than water). Further, we integrated this work with mineralogy-based work that allows reduced molecules to appear as precursors for less “weird” genetic biomolecules, especially through interaction with various mineral species, including borates, molybdates, and sulfates.

Photochemistry in Titan’s dense atmosphere generates a complex mixture of organic molecules that have been deposited on Titan’s surface over time. Requiring no sample pretreatment or handling, the technique of direct analysis in real time (DART), combined with an ion trap mass spectrometer having MS/MS capability, is shown to be an enabling experimental methodology to vaporize, ionize, and structurally characterize organic components of this mixture. A key important development is the use of temperature programmed desorption, accomplished by heating of the probe gas, to examine complex mixtures of organics with a wide range of volatility (polypropylene glycol and tar samples from a petroleum seep). Of particular relevance to astrobiology, this methodology is employed to compare Titan simulants produced in a pulsed discharge from gas mixtures designed to probe mechanistic pathways leading to high molecular weight products.

This study focuses on the condensed phase photochemistry on Titan. In particular, we focus on understanding longer wavelength photochemistry of solid hydrocarbons so simulate photochemistry that could occur based on the UV penetration through the atmosphere and on the evolution of complex organic species in astrobiologically significant regions on Titan’s surface. Here we investigate the oxygenation chemistry involving the condensed Titan’s organic aerosols with water-ice on Titan’s surface – induced by high energy photons simulating the cosmic ray induced chemistry on Titan’s surface.

We are calculating how much material, over time, is ejected from geysers on the moon Enceladus and ends up on the moon Titan, and how this material may be important for pre-biological chemistry on Titan.